1. Field of the Invention
This invention relates in general to a dust collector and, in more particular, to such a device of the type which separates the dust particles from a vortex of air developed in a drum.
2. Description of the Prior Art
There have been various types of cyclone dust collectors developed in the prior art which, as might be represented by Japanese laid-open utility model application No. 56-168054 proposed by the assignee of this invention, typically comprises a dust chamber carrying at an upper part thereof an exhaust pipe in which a funnel-shaped cyclone drum is installed. The drum is formed to open at a lower end thereof into the chamber. With this arrangement, negative pressure is developed in the chamber in order to introduce dust carrying air into the chamber where it is caused to swirl by the circular wall surface of the chamber. The swirling air then makes its way into the drum through its lower opening, thereby further accelerating its swirling speed. Centrifugal force in the drum acts to separate the dust particles contained in the air stream. Dust particles thus centrifugalized are allowed to drop along the inside slope of the funnel-shaped drum all the way onto the bottom where they deposit for subsequent disposal.
However, these conventional dust collectors have been found to suffer from the disadvantage that the vortex of air developed in the drum has tended to blow centrifugalized dust particles about to drop along the inclined inside surface of the drum, often resulting in poor performance of dust collection. One proposed solution is to steepen the inside slope of the funnel-shaped drum to such an extent that the dust particles, upon centrifugalization, are allowed to take a quick fall before they are carried away in the vortex of the air. But this change in the design of the drum would give rise to a problem of increasing the overall height of the collector.
The present invention has been proposed to eliminate the above-mentioned drawback of the conventional cyclone dust collectors.